Losing water: is it evaporation, or a leak?

Water loss is the question where Arizona owners most often assume the expensive answer. In this climate the innocent explanation is genuinely large, so it is worth ruling out first, and it costs nothing.

The bucket test

No other home test holds up as well, since it puts your pool side by side with plain evaporation under the same sun on the same day.

1. Fill a bucket with pool water and stand it on a pool step so it sits partly submerged. This keeps the water in the bucket at the same temperature as the pool, which matters.
2. Mark the water level inside the bucket and mark the pool’s level on the wall or tile. A grease pencil or tape works.
3. Leave everything running normally for 24 hours. Hold off on topping up, and keep swimming to a minimum.
4. Compare the two drops.

• Both dropped by about the same amount → evaporation. Your pool is fine. It is just July.
• The pool dropped noticeably more than the bucket → the difference is your leak.

Run it a second time with the pump off if you get a leak result. If the loss is much worse with the pump running, the leak is more likely on the pressure side of the plumbing; if it is the same either way, it points more toward the shell or fittings.

Why evaporation is so large here

Four things all push the same way: high temperatures, very low humidity, strong sun on the water surface all day, and wind. The result is that a Valley pool can lose a meaningful fraction of an inch a day through the summer with nothing wrong with it at all.

A pool cover changes this substantially, which is the practical answer if the volume of top-up water is what is bothering you.

The knock-on nobody connects

Evaporation removes water and leaves every dissolved mineral behind. Then you top up with hard Valley water, which brings more minerals in.

Do that all summer without ever replacing any water, and calcium hardness climbs steadily. That is the mechanism behind the white calcium ring at the waterline, and it is why a partial drain and refill is a legitimate maintenance step in this metro rather than an admission of failure.

Two habits help:

• Top up little and often rather than letting it fall several inches. A lower level is a more concentrated solution.
• Test hardness at the end of summer, alongside the usual chlorine and pH.

When it is a leak

If the bucket test says leak, get it found before spending anything on the surface. Common sources are the skimmer and its throat, light niches and conduit, returns and fittings, the plumbing itself, and cracks in the shell.

That is leak detection work, a different trade, and it should come before anyone sells you a wash on a pool that will be dug up next month. Once a leak is fixed, a drain and clean or an acid wash makes sense, because you are restoring a pool that will hold what you put in it.

What it costs

From the pricing page.

Get a quote

Start with the bucket test. If it says evaporation, you have saved yourself a service call, which is a fine outcome. If the pool needs restoration work afterwards, send a deck photo and the waterline. We cover Mesa, Gilbert, Chandler, Tempe, Apache Junction, Queen Creek, and Gold Canyon.